Systems for supplying light to a medical device in order to illuminate an area that a medical practitioner is viewing or working upon are generally well known in the art. For example, conventional endoscopes are often supplied with such a system.
Generally, an endoscope is a medical device for insertion into a body passageway or cavity that enables an operator to view and/or perform certain surgical procedures at a site inside a patient's body. As is known, endoscopes may be either rigid or flexible, and generally include a long tubular member equipped with, for example, a miniature viewing device, and in some cases, a working channel for a surgical instrument. The endoscope has a proximal end that remains external to the patient, from which the operator can view the site and/or manipulate a surgical instrument, and a distal end having an endoscope tip for insertion into the body cavity of the patient.
In order to facilitate proper operation, the endoscope typically includes a source of light for illuminating the area the medical practitioner is trying to view and/or work upon. This illumination is usually supplied by an external light source, which typically comprises high powered lamps, such as, for example, a Xenon lamp. Light is transmitted from this light source to the distal portion of the endoscope inserted in the body by a waveguide, such as a fiber optic light cable, in order to guide the light to the scope. Such cables typically incorporate a fiber optic bundle, which comprises a plurality of thin optical fibers made of glass or optical plastic.
A general disadvantage of some scopes of this type is that the transfer of energy from these light sources through these light guides can cause undesired heating of the exterior components of the device. Conventional remedies for this problem involve the use of an infrared filter for the light source. However, in cases where large amounts of energy are involved, undesired heating can still occur even in the absence of excessive infrared radiation.
As further described herein, it is desirable to use in some endoscopes a fiber optic bundle that has a tapered section, for several reasons. First, the use of a taper allows the light guide to receive the light from the external light source at a low numerical aperture and then increase the numerical aperture in order to enlarge the light angle. Second, the taper allows the light to be received at a large diameter, and then reduces this diameter and increases the power density.
However, a disadvantage of these arrangements is that there is a significant loss of power that radiates from the external glass surface of the taper. This contributes significantly to the generation of undesirable heat as discussed above.
Additionally, another disadvantage of these arrangements is that this thinner section of the fiber optic bundle is even more prone to breaking or fracturing during assembly of the instrument.
What is desired, therefore, is a system for transmitting the light required for a medical device that can increase the numerical aperture of the light and can increase the power density of the light. What is further desired is a system for transmitting this light that does not transfer excessive heat to the exterior components of the medical device. What is also desired is a system for transmitting this light that does not easily become damaged during assembly.